A Pakistani military account of the incident provided in December to the U.S. Congress by Pakistan's lobbying firm in Washington, D.C., differs greatly from the American account. It claims a NATO helicopter mistakenly began firing on a Pakistani outpost called Volcano after it had been given incorrect coordinates for the incoming fire. When another outpost, Boulder, attempted to signal the helicopters using illuminating rounds, the helicopters then turned and attacked it as well.
"Any allegation that the NATO troops thought that they were firing on insurgents when they attacked the Volcano and Boulder observation posts is baseless," the Pakistani document says. "NATO was aware that the bases were there when they fired on them. NATO troops are also well aware that terrorists seeking refuge in mountainous areas install themselves in ravines and deep valleys which provide cover from aerial attacks -- not in plain sight on the top of a mountain."
ABC News' Nick Schifrin contributed to this report.